Implanted neurostimulators are used to stimulate neural tissue to treat pain. By means of neurostimulation it is possible to block the pain indicating signals which travel to the brain. Electric pulses are passed between metal electrode contacts implanted into the human body and through the intervening neural tissue. The implanted neurostimulators, in order to be effective in pain treatment are adapted to be controlled by either switching the implanted device on/off, changing the amplitude and frequency of neuro-stimulation, or generating a specific stimulus pattern.
In order to control the implanted neurostimulators a wireless data transmission is commonly used where the implanted neurostimulators communicate bi-directionally with external devices through low frequency electromagnetic transmissions. Typically, a device, external to the human body, acts as a programmer for the implanted device by transmitting radio frequency codes to the implanted device to program its operation.
Such transmitters are typically powered by batteries. Maximum efficiency of the transmitter depends upon generating the largest current through a transmitter antenna coil while consuming the minimum current drained from the battery or other power source. To provide for the efficient low power operation of the transmitter, a high-Q resonant LC network in the transmitter circuit is generally employed. However, since some of the transmitters may be placed in close proximity to living tissue during operation, the external influences, such as human body capacitance and loading effects, may tend to de-tune a high-Q resonant LC network in the transmitter circuit, thus deteriorating the targeted low power operation of the transmitter circuit.
There has been a long lasting need in the field of neurostimulation a way in which to minimize, or completely remove the de-tuning effect of the external influences onto the transmitter circuit in order to achieve efficient low power operation thereof to maximize the useful battery life.
Another problem has existed in the field of wireless communication with implanted neurostimulation devices in that portable transmitters often depend upon either wall adapters or host equipment as power sources. In some cases, however, neither source is available for the transmission device. Additionally, for the wireless transmitter scheme high current pulses are often needed which exceed the capability of low power supplies such as batteries. Therefore, a novel power supply scheme for wireless medical data transmission, as an alternative to a battery, is desirable and long awaited in the field of the neurostimulation.